1. Field of the Invention
The present invention relates generally to an integrally formed safety helmet structure, and more particularly to a safety helmet assembly of a foam cushion filling body, a shell body and a structure body. The foam cushion filling body, the shell body and the structure body bond with each other to form an integrated complex reinforcement structure. The complex reinforcement structure not only makes it possible to manufacture the safety helmet in a lighter and more convenient form, but also has the advantage of high security.
2. Description of the Related Art
A conventional safety helmet has a plastic shell body and an anti-impact filling body formed of foam material by means of heat ing the foam material. The plastic shell body tightly encloses and bonds with the foam filling body to form the safety helmet. FIGS. 1 and 2 show a typical conventional safety helmet.
With respect to the structural design and security of the conventional safety helmet, an (EPS) low-density foam filling body B1 is enclosed in a plastic shell A. A high-density foam filling body B2 is further disposed on inner face of the low-density foam filling body B1 to form a complex foam filling body. The external plastic shell A of the helmet mainly serves to resist against the preliminary impact and thrust force of a sharp object and provide a surrounding converging force for the low-density foam filling body B1. In this case, the low-density foam filling body B1 can provide softer and high-contraction force buffering effect to distribute and transmit the impact force. Under such circumstance, after the strong external impact force is spread, the high-density foam filling body B2 with a material property of higher hardness and frangibility can provide sufficient support strength to bear the external impact force. Therefore, the innermost-layer high-density foam filling body B2 is prevented from breaking to lose its protection effect.
It is known that the high-density foam filling body B2 is positioned in a position nearest to a wearer's head. In the case that the density of the high-density foam filling body B2 is increased to enhance the support strength and protection effect of the high-density foam filling body B2, this often leads to uncomfortable feeling of the wearer when wearing the safety helmet.
Therefore, at the current stage, the arrangement of FIG. 1 is often employed to increase the thickness of the external plastic shell A and thus increase the surrounding converging force thereof so as to ensure that the foam filling body (B1 or B2) is sufficiently able to distribute, transmit and bear external impact force without being over-thickened to affect the volume of the helmet. However, as well known by those who are skilled in this field, when thickening the plastic shell, not only the material cost is increased, but also the total weight of the helmet body is increased and the burden on the wearer is increased. As a result, the wearer will feel uncomfortable when wearing the safety helmet.
In order to improve the above problem, FIG. 2 shows another conventional safety helmet. In this safety helmet, a soft shock-absorbing block body C made of ethylene-vinyl acetate copolymer (EVA) is disposed between the plastic shell A and the foam filling body B. Under such circumstance, a shock-absorbing cushion space D is defined between the plastic shell A and the foam filling body B. By means of the block body C, the space D provides an auxiliary shock-absorbing and cushioning effect to protect the foam filling body B. Accordingly, the external impact force is prevented from directly reaching the foam filling body B to destroy the buffering, distribution and transmission effect of the foam filling body B.
It should be noted that in the conventional safety helmet of FIG. 2, it is necessary to manually adhere or assemble the plastic shell A, the foam filling body B and the block body C layer by layer. Therefore, not only the material cost and manufacturing cost are higher, but also it is time-consuming to manufacture the safety helmet and the manufacturing process cannot be speeded. Moreover, the block body C, the plastic shell A and the foam filling body B are apt to be adhered to each other in incorrect positions due to human error. This will affect the buffering, distribution and transmission effect of the foam filling body B. This is not what we expect.
Basically, with respect to structural design and manufacturing process, the plastic shell and internal structure body of the above conventional safety helmets have some problems in tests and practical use. Therefore, it is tried by the applicant to redesign the assembling structure of the external plastic shell and the internal foam filling body of the safety helmet to greatly enhance the structural strength of the safety helmet and solve the problems existing in the conventional safety helmet. In the condition that the safety helmet is manufactured in a simple form with high security, the safety helmet of the present invention has a structure different from the conventional safety helmet to provide a full protection and support effect and change the transmission/distribution form of the external impact force (or external action force) so as to eliminate the shortcomings of the conventional safety helmet.
For example, the safety helmet structure of the present invention apparently improves the shortcoming of the conventional safety helmet structure that the internal structure body (or foam filling body) of the conventional safety helmet is unable to effectively distribute and transmit various external impact forces to the respective regions of the helmet body for every part of the safety helmet structure to uniformly bear various impact forces.
The present invention provides a multilayer helmet structure design, which is able to bear various external impact forces. In the helmet structure, the foaming density of the outermost-layer structure is smaller than the foaming density of the middle-layer structure so as to achieve better collapsing and distribution effect. The middle-layer structure has sufficient structural strength or hardness to bear and resist against the distributed impact force without transmitting the impact force directly to the interior of the helmet. In addition, in condition that the innermost-layer structure of the helmet has sufficient strength, the foaming density of the innermost-layer structure is smaller than the foaming density of the middle-layer structure so as to further provide impact force distribution, transmission and absorption effect. This can improve and lower the uncomfortable feeling of a wearer.
In a preferred embodiment, the foaming density of the solid foam granules or materials progressively increases from the regions of the outermost-layer and innermost-layer structures to the region of the middle-layer structure. In addition, the safety helmet assembly has higher structural strength than the conventional safety helmet in all directions or regions so that the safety helmet assembly is able to fully bear external impact or lateral impact pressure. Furthermore, in condition of high security, the safety helmet assembly is designed with a highly lightweight structure to widen the application range of the safety helmet. None of the conventional safety helmets substantially has the advantages of the present invention.